fix(voice): restore voice features and apply critical optimizations

Voice Feature Restoration:
- Implemented full Redis pub/sub pipeline for real-time voice data
- Added VOICE_PCM and VOICE_ACTIVE_USER Redis channels
- Implemented EventBroadcaster.voicePcmData() and voiceActiveUser() methods
- Extended backend redis-bridge to subscribe to voice channels
- Updated backend WebSocket server for binary PCM broadcast
- Replaced globalThis PcmBroadcaster pattern with proper EventBroadcaster DI
- Fixed root cause: PcmBroadcaster functions were never initialized

Bug Fixes:
- Fixed prism-media version conflict (2.0.0-alpha.0 → 1.3.5)
- Fixed type inconsistency in commandHandler.ts (AudioPlayerStatus → string)

Critical Optimizations:
- P1.1: Fixed unbounded memory growth in aiAnalyzer (added LRU caching, max 10K entries)
- P1.2: Converted sync file I/O to async in audio hot paths (recorder, sessionRecording)
- P1.3: Replaced process.exit(1) with proper error handling (bootstrap, aiAnalysisWorker)

Code Quality:
- Removed unused logger field in EventBroadcaster
- Replaced console.* with structured logger.* calls (player, decoder)
- Fixed typos and removed commented debug code
- Added DatabaseError class for better error handling

Files Modified: 18 (discord-gateway: 14, backend: 3, root: 1)
Architecture: Discord → EventBroadcaster → Redis → Backend WebSocket → Frontend

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/discord-gateway/src/shared/config/config.ts

@@ -189,7 +189,7 @@ const configSchema = z
   })
   .superRefine((value, ctx) => {
     if (!value.AI_ANALYSIS_ENABLED) {
-      // Continue to database validationa
+      // Continue to database validation
     } else if (!value.AI_LLM_API_KEY) {
       ctx.addIssue({
         code: z.ZodIssueCode.custom,

services/discord-gateway/src/shared/errors/errors.ts

@@ -25,6 +25,13 @@ export class AudioError extends AppError {
   }
 }
 
+export class DatabaseError extends AppError {
+  constructor(message: string) {
+    super(message, "DATABASE_ERROR", 500);
+    this.name = "DatabaseError";
+  }
+}
+
 export class VoiceConnectionError extends AppError {
   constructor(message: string) {
     super(message, "VOICE_CONNECTION_ERROR", 500);